The invention relates to a device for recording at least one information block in track in a recordable area on a record carrier, which information block comprises data words and error correction words for correcting errors within the information block, and which track has preformed position information indicative of positions for recording the information blocks, which device comprises recording means for recording marks representing the information blocks and control means for recording and retrieving position data indicative of the position of the recorded information blocks.
The invention further relates to a method of recording at least one information block in track in a recordable area on a record carrier, which information block comprises data words and error correction words for correcting errors within the information block, and which track has preformed position information indicative of positions for recording the information blocks, which method comprises recording marks representing the information blocks and recording and retrieving position data indicative of the position of the recorded information blocks.
The invention further relates to a record carrier comprising a track in a recordable area for recording at least one information block, which information block comprises data words and error correction words for correcting errors within the information block, and which track has preformed position information indicative of positions for recording the information blocks and preformed control information for controlling the recording process.
A device and method for recording information signals on a record carrier is known from U.S. Pat. No. 5,124,966 (PHN12887). The information is encoded in information block comprising data words and error correction words for correcting errors within the information block. The device comprises recording means for recording marks representing the information blocks. The information of at least one information block is modulated to a modulated signal and recorded in the track at predefined locations indicated by preformed track position information. The device has control means for recording and retrieving position data indicative of the position of the recorded information blocks in a special area on the record carrier. A temporary table of contents (TOC) is recorded in the special area and retrieved during the recording of subsequent information signals. The temporary TOC represents position data indicative of the position of the recorded information blocks. Each time an information signal is recorded, additional data is to be recorded in the special area. For retrieving the actual status of the last recorded information the special area must be completely read. In a write once type of record carrier like CD-R the position data cannot be overwritten, and hence the amount of position data may become large.
It is an object of the invention to provide a more flexible and reliable system for recording position data.
For this purpose, the device as described in the opening paragraph is characterized in that the control means comprise mapping means for determining in which region the information block is recorded, the region being one of a number of consecutive regions constituting the recordable area, and for recording a random signal unit in a unit location in a mapping area of the record carrier, the unit location in the mapping area being indicative of said region, and the unit length of the random signal unit being substantially smaller then the length of said information block, and detecting means for retrieving from said mapping area if a region contains at least one information block by detecting the presence of the recorded random signal units. The method as described in the opening paragraph is characterized in that the method comprises determining in which region the information block is recorded, the region being one of a number of consecutive regions constituting the recordable area, and recording a random signal unit in a unit location in a mapping area of the record carrier, the unit location in the mapping area being indicative of said region, and the unit length of the random signal unit being substantially smaller then the length of said information block, and retrieving from said mapping area if a region contains at least one information block by detecting the presence of the recorded random signal units. A random signal unit indicates a signal segment representing data that may have any value, including a known and/or fixed pattern. This has the advantage that for detecting the amount of data recorded in the recordable area the amount of position data to be retrieved at most has the size of the mapping area. Hence response time of the device to a recording request will be short.
The invention is based on the following recognition. First the inventors have seen that a substantial amount of the response time of a recording device to a recording request is due to the amount of position data to be read. Secondly the inventors have seen that the amount of position data can be reduced by recording a mapping area using short random signal units. The unit length is smaller then the length of the information block and therefore no information can be retrieved from the recorded random signal units, but the fact that the unit location has been recorded or not provides information about the status of the corresponding region in the recordable area of the disc.
According to a second aspect of the invention the record carrier as described in the opening paragraph is characterized in that the control information comprises recorded area management information indicative of parameters to be recorded for managing a mapping area indicating in which regions information blocks are recorded, the region being one of a number of consecutive regions constituting the recordable area, the mapping area having unit locations for recording random signal units, the unit location in the mapping area being indicative of said region, and the unit length of the random signal unit being substantially smaller then the length of said information block. In an embodiment of the device the control means are arranged for retrieving control information from the record carrier, the control information comprising recorded area management information indicative of parameters to be recorded for managing the mapping area. This has the advantage that the recording device can retrieve position data from a mapping area in dependence on the type of record carrier. Hence different types of record carriers and different configurations of the mapping area can be used in a single recording device.
In an embodiment of the device, where the preformed position information is encoded in address frames having a frame length, the unit length is substantially equal to the frame length. This has the advantage that the unit locations correspond to address frames, and can therefore be easily located and read using the circuitry already required in the device for reading information blocks.
It is noted that U.S. Pat. No. 5,293,566 describes a recording device for recording a record carrier of a rewriteable type. In a disc control region the address of a latest recorded sector is recorded. This region is rewritten each time a new information signal is recorded. Hence reading information from the disc control region which is often rewritten may become unreliable because of wear of that part of the record carrier; and such method is not suitable for write once type of record carriers.